Wednesday, May 22, 2024

2S Cell Charger With An Integrated Boost Converter

The EV2639A-R-00B from Monolithic Power Systems is the reference design for a 2S charger with an integrated boost converter. The reference design features a highly integrated, flexible switch-mode charge management IC that can take input between 4V and 5.75V. It can charge both Li-Ion and Li-Po cells with a 2.5A charge current. The reference design also provides a voltage-based fuel gauge indication through LED drivers present on the circuit. This design is highly customisable and allows users to increase the discharge current up to 5A. The board offers a programmable timer to prevent prolonged charging of a dead battery. The reference design can be used as a standalone charger or it can be employed in a mobile, tablet or any other portable device.

The efficiency of the module is shown in the image below:

Graphs showing the efficiency of the EV2639A module

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In this reference design, the MP2639A works in a step-up mode to charge the 2-cell battery from the 5V input. In absence of the charger, the module is in discharge mode, where it works in a step-down mode to give an output of 5V. For the charging function, the battery charging IC detects the battery voltage and based on the voltage charges the battery in three phases: trickle current, constant current, and constant voltage.

Circuit diagram of EV2639A module

Circuit diagram of EV2639A module

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  • Bidirectional operation for charging or discharging
  • 2- Cell Li-ion or Li-polymer
  • Cell balance and protection escorting for two-series cell charging
  • Light-load detection for discharge mode
  • Integrated voltage-based fuel gauge using four LED drivers
  • Take 5V input and charge 2S cell

Safety Features

  • input overvoltage protection (OVP)
  • battery over-voltage protection (OVP)
  • thermal shutdown
  • battery temperature monitoring
  • programmable timer to prevent prolonged charging of a dead battery.

You can find additional details and design resources of this reference design here.


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